1. Field of the Invention:
This invention relates to a highly hard thin film having fine crystalline ceramic particles dispersed in a metallic matrix phase and a method for the production thereof. More particularly, it relates to a hard wear-resistant film which has a highly hard ceramic surface, exhibits satisfactory adhesiveness to a substrate, excels in resistance to crushing and proves useful as high-strength materials, wear-resistant materials, and high temperature-resistant materials in a wide variety of industrial applications.
2. Description of the Prior Art:
As wear-resistant coating materials for protecting machine parts and tools against wear and scratches, such materials as TiN, TiC, WC, and Al--Ti--N alloy have been heretofore used. The films of these materials are generally formed by such physical vapor deposition processes as the reactive sputtering process and the ion plating process and are used as wear-resistant films. In order for these films to acquire ample hardness, they are required to have their nitrogen content or carbon content increased to a certain extent. The increase of the nitrogen or carbon content in the film, however, has the possibility of inflicting persistent residual stress on the film after the treatment. Further, since the crystalline particles of the columnar structure precipitate in the film depending on the conditions adopted for the deposition of film, a fracture suffered to occur inside the film possibly exerts an adverse effect on the normal part of the film surrounding the fracture and thus the film becomes mechanically brittle.
Further, the formed film is required to be dense and to excel in adhesiveness to a substrate. In general, preparatorily to the deposition of a desired hard film on a given substrate, the substrate is given such pretreatments as degreasing and etching. Then, the desired hard film is directly deposited on the freshly pretreated substrate. In the case of the film thus deposited, since the physical characteristics of the substrate and those of the film differ extremely at times, the adhesiveness of the film to the substrate becomes insufficient. To avoid this disadvantage, the practice of preheating the substrate and then depositing the film on the preheated substrate has been in vogue. In spite of these elaborate treatments, the film is still at a disadvantage in manifesting a columnar crystalline structure which makes the film mechanically brittle.